{"action":"opened","issue":{"url":"https://api.github.com/repos/Zimmi48/bugzilla-test/issues/1330","repository_url":"https://api.github.com/repos/Zimmi48/bugzilla-test","labels_url":"https://api.github.com/repos/Zimmi48/bugzilla-test/issues/1330/labels{/name}","comments_url":"https://api.github.com/repos/Zimmi48/bugzilla-test/issues/1330/comments","events_url":"https://api.github.com/repos/Zimmi48/bugzilla-test/issues/1330/events","html_url":"https://github.com/Zimmi48/bugzilla-test/issues/1330","id":252919366,"number":1330,"title":"Inversion anomaly: Failure \"try_find\".","user":{"login":"Zimmi48","id":1108325,"avatar_url":"https://avatars2.githubusercontent.com/u/1108325?v=4","gravatar_id":"","url":"https://api.github.com/users/Zimmi48","html_url":"https://github.com/Zimmi48","followers_url":"https://api.github.com/users/Zimmi48/followers","following_url":"https://api.github.com/users/Zimmi48/following{/other_user}","gists_url":"https://api.github.com/users/Zimmi48/gists{/gist_id}","starred_url":"https://api.github.com/users/Zimmi48/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Zimmi48/subscriptions","organizations_url":"https://api.github.com/users/Zimmi48/orgs","repos_url":"https://api.github.com/users/Zimmi48/repos","events_url":"https://api.github.com/users/Zimmi48/events{/privacy}","received_events_url":"https://api.github.com/users/Zimmi48/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2017-08-25T14:31:42Z","updated_at":"2017-08-25T14:31:42Z","closed_at":null,"body":"Note: the issue was created automatically with bugzilla2github tool\n\n# Bugzilla Bug ID: 220\nDate: 2002-11-04 17:32:03 +0100\nFrom: dachuan.yu@yale.edu\nTo:   \n\nLast updated: 2002-11-04 17:32:03 +0100\n\n\n## Bugzilla Comment ID: 540\nDate: 2002-11-04 17:32:03 +0100\nFrom: dachuan.yu@yale.edu\n\nFull_Name: Dachuan Yu\nVersion: 7.3.1\nOS: Red Hat Linux 7.1\nSubmission from: vodka.cs.yale.edu (128.36.229.211)\n\n\nWe met with a problem when encoding something using Coq 7.3.1.\nHere is a simplified version. \n\nFirst, we define a \"Type\" T which depends on a \"nat\" n as follows: \n\nFixpoint T[n:nat] : Type := \n Cases n of \n | O => (nat -> Prop) \n | (S n') => (T n') \n end. \n\nThen, we define a relation R as follows: \n\nInductive R : (n:nat)(T n) -> nat -> Prop := \n  | RO : (Psi:(T O); l:nat) \n          (Psi l) -> (R O Psi l) \n  | RS : (n:nat; Psi:(T (S n)); l:nat) \n          (R n Psi l) -> (R (S n) Psi l). \n\nNext, we define two objects of type (T O). \n\nDefinition Psi00 : (nat -> Prop) := [n:nat] False. \nDefinition Psi0 : (T O) := Psi00. \n\nSo far everything is ok. Now we want to prove the following lemma: \n\nLemma Inversion_RO : (l:nat)(R O Psi0 l) -> (Psi00 l). \n\nThis lemma is true because the premise is false. It seems easily provable\nusing the inversion tactic on (R O Psi0 l). However, when I did that ,\nI got an error: \n\n    Anomaly: Failure \"try_find\". Please report. \n\nIt seems that we may get around this problem by manually writing the proof\nterm,\nas opposed to using tactics. Anyway, the problem above still looks like a bug.\n\n\n\n\n## Bugzilla Comment ID: 542\nDate: 2002-11-06 10:23:09 +0100\nFrom: dachuan.yu@yale.edu\n\nHugo Herbelin <coq-bugs@pauillac.inria.fr>\n  Hi Dachuan Yu,\n\n> We met with a problem when encoding something using Coq 7.3.1.\n> Here is a simplified version. \n> \n> First, we define a \"Type\" T which depends on a \"nat\" n as follows: \n> \n> Fixpoint T[n:nat] : Type := \n>  Cases n of \n>  | O => (nat -> Prop) \n>  | (S n') => (T n') \n>  end. \n> \n> Then, we define a relation R as follows: \n> \n> Inductive R : (n:nat)(T n) -> nat -> Prop := \n>   | RO : (Psi:(T O); l:nat) \n>           (Psi l) -> (R O Psi l) \n>   | RS : (n:nat; Psi:(T (S n)); l:nat) \n>           (R n Psi l) -> (R (S n) Psi l). \n> \n> Next, we define two objects of type (T O). \n> \n> Definition Psi00 : (nat -> Prop) := [n:nat] False. \n> Definition Psi0 : (T O) := Psi00. \n> \n> So far everything is ok. Now we want to prove the following lemma: \n> \n> Lemma Inversion_RO : (l:nat)(R O Psi0 l) -> (Psi00 l). \n> \n> This lemma is true because the premise is false. It seems easily provable\n> using the inversion tactic on (R O Psi0 l). However, when I did that ,\n> I got an error: \n> \n>     Anomaly: Failure \"try_find\". Please report. \n> \n> It seems that we may get around this problem by manually writing the proof\n> term,\n> as opposed to using tactics. Anyway, the problem above still looks like a\nbug.\n\n  It is a bug. It is now solved on coqcvs.inria.fr (tag V7-3bugfix).\n\n  Thanks for report.\n\n  Hugo\n\n\n## Bugzilla Comment ID: 541\nDate: 2007-07-04 17:03:18 +0200\nFrom: dachuan.yu@yale.edu\n\nFixed in cvs (main and V7-3bugfix) [HH 11/6/02]\n\n"}}
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